High load time to time high iowait

the_bobara

Well-Known Member
PartnerNOC
Sep 23, 2004
92
0
156
Bulgaria
cPanel Access Level
Root Administrator
Hello,
i have big problem with one of my servers.
I`m running CentOS 4.3 64bit with lastest stable cpanel.
Sometimes (a lot of times a day) the server load increase very fast. The server is working with load 0.x or 1.x and for seconds the load reach 80 - 100 - 140 sometimes even more than 250. When this happen i just stop apache, but this cant be the way.
I have read all the posts here, i spent a lot of nights googling but nothing helped. My current kernel is Linux 2.6.9-42.ELsmp #1 SMP the kernel before current was 2.6.9-34.ELsmp i changed a lot of kernels but nothing fixed my server. Now it happens once a day, but sometimes all day my server is crashing. Tell me what to do, i tried all the things that was posted here, has someone still have this problem? how the other manage to fix it?

here is the munin log of the system
P.S. sorry for my bad English
 

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avijit

Well-Known Member
Jul 26, 2004
116
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166
India
In the shell run "top -c" to get the idea on what is causing the loads to spike to that level and then you can troubleshoot it.
 

spector

Well-Known Member
Jun 27, 2005
51
0
156
I had exacly same issue with centos default install - high cpu usage by "iowait". You need to upgrade kernel manualy to newest (like 2.6.17.7) and problem will be gone instantly!
 

AndyReed

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PartnerNOC
May 29, 2004
2,221
4
193
Minneapolis, MN
the_bobara said:
I`m now with 2.6.9-42.ELsmp kernel, i tried a lot of kernels. I have tried 2.6.9.34, 2.6.9.39 and a other...
Although it is very hard to say without looking into your server, the problm might be something else other than the Kernel. It might be a hardware problem, or your server might come under serious attack.
 

HostMerit

Well-Known Member
Oct 24, 2004
164
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166
New Jersey, USA
cPanel Access Level
DataCenter Provider
We were using 2.6.14.6 and another kernel one ver higher with iowait / some load issues. The server just seemed sluggish.

2.6.17.8 seems to have solved all issues.

Dual Xeon 2.8 with SATA's.
 

nickp666

Well-Known Member
Jan 28, 2005
769
2
168
/dev/null
AndyReed said:
Although it is very hard to say without looking into your server, the problm might be something else other than the Kernel. It might be a hardware problem, or your server might come under serious attack.
I have the same issue which only occurred after the kernel upgrade, somewhere on the vbulletin forums is a large thread about it, seems to be an issue with that particular kernel
 

bin_asc

Well-Known Member
Jul 18, 2005
280
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166
It was said on vb forums, that a kernel 2.6.9-42.0.2 should be used, because the newer one is a kernel panic release, and it was causing issues in relation with the quota callouts.